Re: [OT] What is DEL for?
On Thu, 22 Feb 2001, [EMAIL PROTECTED] wrote: Otto Stolz [mailto:[EMAIL PROTECTED]] wrote: Dear Unicoders, again, I have inadvertently sent a contribution to a member rather than to the whole list, because the Unicode list sets the Reply-to header in an utmost inconvenient and unexpected manner. Here is a copy for the list. I hope I will not mistype the address. I really wish that I simply could use the reply-to-sender function of my MUA to answer to the Unicode list. ... Or maybe you need a mail client that allows you to apply a special rule to messages that come from this list such that any reply you send to a list message defaults to the address in the To: line rather than that in the From: or Reply To: line of the original message. I agree with you about the specific case of the Reply-To: header, but I think that it might be a good idea to change the list setup in other ways. For instance, the current setup seems to remove all In-Reply-To: and References: headers. This is a problem since it breaks the ability of my email program (Gnus) to do threading, for no particularly good reason. In fact, I believe that all headers except for a those in a particular list are removed. Another annoyance is that no special headers are used to indicate that the message is in fact from this mailing list, so that you have to use the Sender: header etc. to do mail splitting, which is also annoying. -- Gaute Strokkeneshttp://www.srcf.ucam.org/~gs234/ I'm using my X-RAY VISION to obtain a rare glimpse of the INNER WORKINGS of this POTATO!!
Re: [OT] What is DEL for?
Dear Unicoders,
again, I have inadvertently sent a contribution to a member rather than
to the whole list, because the Unicode list sets the Reply-to header in
an utmost inconvenient and unexpected manner.
Here is a copy for the list. I hope I will not mistype the address.
I really wish that I simply could use the reply-to-sender function
of my MUA to answer to the Unicode list.
Best wishes,
Otto Stolz
--- Forwarded mail from [EMAIL PROTECTED] ("Otto Stolz")
Date: Wed, 21 Feb 2001 19:21:25 +
In a message dated 2001-02-21 07:03:46 Pacific Standard Time,
[EMAIL PROTECTED] writes:
What is the function of ASCII control code 0x7F (DEL) in text interchange?
Am 2001-02-21 um 16:24 h hat [EMAIL PROTECTED] geschrieben:
In MS-DOS, the TYPE command displays the glyph associated with
U+2302 HOUSE (a.k.a. INVERTED HOME PLATE).
But this is not because it's ASCII DEL, but rather because it's
HOUSE (IBM character designator SM79), in CP 437 and CP 850.
I have donated my IBM books on character encoding to somebody who will
use them better than I could. From what I remember, the DOS codes came
in two flavours: the "Display code" which placed graphic characters in
255 of the 256 codepoints available, and the "Data code" which contained
the ASCII control characters, in their proper places (mostly). So,
CP 437 Display has the HOUSE at 0x7F, whilst CP 437 Data has the DEL-
control at 0x7F. If you send the bytes to the display (physical, or
emulated), Data code is assumed, so the HOUSE will be displayed.
I reckon, U+2032 HOUSE was included in Unicode, for this very reason.
Cf. ftp://ftp.unicode.org/Public/MAPPINGS/VENDORS/MISC/IBMGRAPH.TXT.
(The tables in ftp://ftp.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/PC/
only account for the Data variant of the various DOS code pages.)
Best wishes,
Otto Stolz
PS: Above, I said "mostly", because the meanings of three control
codes have been permuted relative to ASCII, in the DOS Data codes.
---End of forwarded mail from [EMAIL PROTECTED] ("Otto Stolz")
RE: [OT] What is DEL for?
From: Marco Cimarosti [mailto:[EMAIL PROTECTED]] This also casts some light on the fact that some fonts (notably JIS fonts) have a big black box glyphs at position 0x7F: it is probably for overwriting a character already printed on paper, so that it cannot be read anymore. Probably not. A big black box (big hollow boxes are also used for this) is a polite way to represent a character which has no glyph. But a few people also raised some "contemporary" issues, which is what I was trying to obtain with my question: Doug Ewell wrote: You have probably already tested this, but in Windows [...] it simply displays as a box [...] Actually, I wasn't expecting this. I tested a file containing the text "ABC*DEF" (where * = DEL) and expected that at least one process would display "ABDEF" where the DEL character had deleted the C. I would not expect any system to display "ABDEF". DEL is a bit of a "one way" character - it triggers a deletion when sent as (interactive) input, but should not cause the same effect when stored as data. Note that this is an "active" character which exists in Unicode for compatibility issues (in this case, there's quite a lot to compat with), and does not fit neatly into the character encoding model. Specifically, DEL is meant to be interpreted by a filter between sender and receiver, as are all the code points 0x00-0x1F. Many of these no longer require intermediary interpretation (example: carriage return (0x0D) originally triggered physical action on the receiving printer, but now is a logical marker). John Cowan wrote: In general it has none. Some systems interpret it (erroneously) as either "cancel previous character" (usually BS) or "interrupt process" (usually ^C). Which systems interpret 0x7F as "interrupt process"? I know that this would be 0x03 in DOS (^C), and 0x03, 0x04 or 0x1A in Unix (^C, ^D, and ^Z, respectively), but I know nothing about other systems, e.g. Macintosh. HPUX by default interprets DEL as "interrupt process", when received from stdin. Valery E Ushakov (Uwe) wrote: On DEC (and, I belive other) terminals the -- "Rubout" key (PC keyboards has "BackSpace" key in this position) generates DEL. So emacs, The One True Editor :-), uses ^H key (i.e. backspace) for help - which causes a lot of confusion for new users who have PC keyboards that generate backspace (^H) for -- key. This leads me to some more questions: 1) What happens if emacs loads Doug Ewell's text file (I.e. a text file containing "ABCdelDEF") and then saves it? Would the file's content be changed to "ABDEF"? No. That DEL would be loaded as data, not sent to the input handler, which is what interprets DEL as "delete character". 2) Could emacs be invoked with a text file as the keyboard input? I mean a thing like: emacs mycmd.txt Probably, but it wouldn't be done like that, I think. You could certainly write some elisp to do this. 3) If 2 above is possible, what would happen if mycmd.txt contains "ABCdelDEF^X^Wmytxt.txtnewline"? Would mytxt.txt contain "ABDEF"? (Note: I understand that ^X+^W+filename is the command to save a new file in emacs; sorry if this is wrong) In principle, this would work. HTH, /|/|ike
RE: [OT] What is DEL for?
Mike Ayers wrote: This also casts some light on the fact that some fonts (notably JIS fonts) have a big black box glyphs at position 0x7F: [...] Probably not. A big black box (big hollow boxes are also used for this) is a polite way to represent a character which has no glyph. I don't think this is the case -- at least not for MS Mincho, the only Japanese font that I have at hand -- because the glyph for all other missing characters is a small circle; only DEL is a black square. _ Marco
RE: [OT] What is DEL for?
On Thu, 22 Feb 2001, Marco Cimarosti wrote: Frank da Cruz wrote: DEL does indeed have a use in plain text files that are encoded with Shift-In / Shift-Out to switch between left and right halves of (say) ISO 8859-1 without having to actually put 8-bit characters in the file. This sounds quite double-byte Greek to me but, if my understanding is correct, it could be an interesting precedent. This is what I think I understood: - Same 8-bit character sets (e.g. Latin-1) may be encoded in 7-bit bytes. - The same values 0x20..0x7F are used both to represent characters 0x20..0x7F themselves (the "left half", I guess) and characters 0xA0..0xFF (the "right half", I guess). - The Shift-In and Shift-Out control characters (0x0F and 0x0E) are inserted in the text to signal whether or not, from that point onwards, 0x80 has to be added to each byte's value. - In this scheme, DEL (0x7F) is used to represent both character 0x7F itself and 0xFF (= 0x7F + 0x80 = LATIN SMALL LETTER Y WITH DIAERESIS). Not at the same time. 02/00 and 07/15 are used to represent U00A0 and U00FF ONLY when the right half of ISO 8859-1 (there is the name for this, but I forgot) is designated as G1(or G2/G3) (in advance) and (later) invoked onto GL with SO (or LS2/LS3). The meaning of 07/15 and 02/00 are preserved when ISO 646 is invoked on GL, I guess. If you ACK my understanding, the question is: how do these 0x7F bytes (representing 0xFF characters) interact with terminals/host communication? I think a decent terminal (emulator) with the proper understanding of ISO-2022 would not get confused :-) Ditto for "higher" levels of ISO-2022 character-set invocation (LS3, etc). Could I find ISO-2022 on-line (or an unofficial explanation of it)? The answer was given yesterday :-). Pls, go to http://www.ecma.ch and look for ECMA-35 (which is ISO-2022). Unlike ISO, ECMA has made their standard documents available on-line for quite a while. Jungshik Shin
RE: [OT] What is DEL for?
On Thu, 22 Feb 2001, Marco Cimarosti wrote: Could I find ISO-2022 on-line (or an unofficial explanation of it)? Yes. ISO-2022 = ECMA-35 search in www.ecma.ch for ecma-35.pdf BTW, here what it says about delete: 6.2.1 Character DELETE Name: DELETE Acronym: DEL Coded representation: 07/15 DEL was originally used to erase or obliterate an erroneous or unwanted character in punched tape. DEL may be used for media-fill or time-fill. DEL characters may be inserted into, or removed from, a CC-data-element without affecting its information content, but such action may affect the information layout and/or the control of equipment. On request, ECMA also sends printed copies of their standards, and also a cdrom containing all of their standards. All this for free. Ciao Pierpaolo
Re: [OT] What is DEL for?
On Wed, Feb 21, 2001 at 06:29:29 -0800, Marco Cimarosti wrote: What is the function of ASCII control code 0x7F (DEL) in text interchange? Particularly, what effect or interpretation might it have in communication protocols, terminal protocols and, especially, inside text files? My interest is about the function of this character in *contemporary* platforms and software, although I wouldn't dislike historical information, as far as it is clearly flagged as such. AFAIK, the history is that on punched media (cards, paper tape) DEL was used to delete a character as it was represented as holes in all positions. For paper tape the following demonstrates it nicely: $ echo -ne '\177' | /usr/games/ppt ___ | .ooo| ___ On DEC (and, I belive other) terminals the -- "Rubout" key (PC keyboards has "BackSpace" key in this position) generates DEL. So emacs, The One True Editor :-), uses ^H key (i.e. backspace) for help - which causes a lot of confusion for new users who have PC keyboards that generate backspace (^H) for -- key. SY, Uwe -- [EMAIL PROTECTED] | Zu Grunde kommen http://www.ptc.spbu.ru/~uwe/| Ist zu Grunde gehen
Re: [OT] What is DEL for?
In a message dated 2001-02-21 07:03:46 Pacific Standard Time, [EMAIL PROTECTED] writes: What is the function of ASCII control code 0x7F (DEL) in text interchange? Particularly, what effect or interpretation might it have in communication protocols, terminal protocols and, especially, inside text files? You have probably already tested this, but in Windows text editors (even Word) it simply displays as a box. In MS-DOS, the TYPE command displays the glyph associated with U+2302 HOUSE (a.k.a. INVERTED HOME PLATE). I don't know if this would be different using the ANSI X3.64 emulator (ANSI.SYS). Actually, I wasn't expecting this. I tested a file containing the text "ABC*DEF" (where * = DEL) and expected that at least one process would display "ABDEF" where the DEL character had deleted the C. I guess this means that on Microsoft operating systems, DEL is treated just like any other character (although a glyph may not be available). -Doug Ewell Fullerton, California
Re: [OT] What is DEL for?
Which systems interpret 0x7F as "interrupt process"? I know that this would be 0x03 in DOS (^C), and 0x03, 0x04 or 0x1A in Unix (^C, ^D, and ^Z, respectively), but I know nothing about other systems, e.g. Macintosh. Very long ago, in the Seventh Edition of Unix, the default interrupt character was DEL, because it was (as Uwe writes) available on old terminals without the need to hold down any shift key. But even then most people changed it to ^C in actual practice. Yes, DEL has many, many uses in the terminal-to-host direction, as do most other control characters. I probably use DEL about 1000 times a day. We all should be familiar with the BS/DEL confusion, but those who aren't might want to take a look at: http://www.columbia.edu/kermit/backspace.html 1) What happens if emacs loads Doug Ewell's text file (I.e. a text file containing "ABCdelDEF") and then saves it? Would the file's content be changed to "ABDEF"? No. As part of a text file, DEL has no known significance on any system. You can never know what all its uses are. If anybody hopes to be able to recycle or abolish it, that would be a bad idea. ASCII (ISO 646 IRV) must remain stable and inviolable for all time. DEL does indeed have a use in plain text files that are encoded with Shift-In / Shift-Out to switch between left and right halves of (say) ISO 8859-1 without having to actually put 8-bit characters in the file. Ditto for "higher" levels of ISO-2022 character-set invocation (LS3, etc). DEL is used by some (non-ANSI-X3.64) terminals for specific purposes, and others for padding. - Frank
Re: [OT] What is DEL for?
Marco Cimarosti wrote: Which systems interpret 0x7F as "interrupt process"? I know that this would be 0x03 in DOS (^C), and 0x03, 0x04 or 0x1A in Unix (^C, ^D, and ^Z, respectively), but I know nothing about other systems, e.g. Macintosh. Very long ago, in the Seventh Edition of Unix, the default interrupt character was DEL, because it was (as Uwe writes) available on old terminals without the need to hold down any shift key. But even then most people changed it to ^C in actual practice. 1) What happens if emacs loads Doug Ewell's text file (I.e. a text file containing "ABCdelDEF") and then saves it? Would the file's content be changed to "ABDEF"? No. As part of a text file, DEL has no known significance on any system. -- There is / one art || John Cowan [EMAIL PROTECTED] no more / no less || http://www.reutershealth.com to do / all things || http://www.ccil.org/~cowan with art- / lessness \\ -- Piet Hein
Re: [OT] What is DEL for?
On Wed, Feb 21, 2001 at 09:42:53 -0800, Marco Cimarosti wrote: 1) What happens if emacs loads Doug Ewell's text file (I.e. a text file containing "ABCdelDEF") and then saves it? Would the file's content be changed to "ABDEF"? No. I don't think any program interprets file contents in this way. 2) Could emacs be invoked with a text file as the keyboard input? No. It needs a reall tty. SY, Uwe -- [EMAIL PROTECTED] | Zu Grunde kommen http://www.ptc.spbu.ru/~uwe/| Ist zu Grunde gehen
Re: [OT] What is DEL for?
Frank da Cruz wrote: DEL does indeed have a use in plain text files that are encoded with Shift-In / Shift-Out to switch between left and right halves of (say) ISO 8859-1 without having to actually put 8-bit characters in the file. Ditto for "higher" levels of ISO-2022 character-set invocation (LS3, etc). I did not think you could put a 96-element character set such as 8859-1-high-half (ESC 02/13 04/01) into G0, but I see by checking ISO 2022 (ECMA-35) that you can, overriding the usual meanings of SP and DEL. -- There is / one art || John Cowan [EMAIL PROTECTED] no more / no less || http://www.reutershealth.com to do / all things || http://www.ccil.org/~cowan with art- / lessness \\ -- Piet Hein
Re: [OT] What is DEL for?
Marco Cimarosti wrote: What is the function of ASCII control code 0x7F (DEL) in text interchange? Particularly, what effect or interpretation might it have in communication protocols, terminal protocols and, especially, inside text files? In general it has none. Some systems interpret it (erroneously) as either "cancel previous character" (usually BS) or "interrupt process" (usually ^C). My interest is about the function of this character in *contemporary* platforms and software, although I wouldn't dislike historical information, as far as it is clearly flagged as such. Historically it was used to "rub out" existing characters on punched paper tape. Because it had all bits set (from a 7-bit viewpoint), it could always be punched over any other character without the need of changing holes to non-holes. Therefore, punched paper tape systems ignored it. -- There is / one art || John Cowan [EMAIL PROTECTED] no more / no less || http://www.reutershealth.com to do / all things || http://www.ccil.org/~cowan with art- / lessness \\ -- Piet Hein
